The present invention relates to a plasma processing apparatus for applying an etching processing to a board-like sample, such as a semiconductor wafer, within a processing chamber inside a vacuum vessel by taking advantage of plasma which is generated within this processing chamber.
There exists a plasma processing apparatus for performing a processing such as an etching of a sample, e.g., a semiconductor wafer, by mounting the sample on a sample stage, and taking advantage of plasma which is generated over the sample. In this plasma processing apparatus, temperature of the sample exerts a tremendous influence on its processing performance. Accordingly, temperature of the sample stage is controlled into a desired temperature distribution.
Mentionable control methods for controlling the sample-stage temperature are as follows: A heat-exchanging liquid, which is under temperature control, is caused to flow inside the sample stage. Otherwise, a heater is built-in inside the sample stage, thereby performing the heat control over the sample stage.
Here, the sample, which is mounted on the sample stage, is caused to adhere to this sample stage by taking advantage of static electricity. An exceedingly-thin insulating film is formed on the sample stage's surface on which the sample is mounted. This insulating film is formed by using a spraying method, or by pasting an exceedingly-thin insulating plate using an adhesive agent or the like. Here, the following configuration is employed: Namely, an electrode is formed on the lower-surface side of the insulating film, then applying a voltage to this electrode. This voltage application gives rise to the occurrence of polarization inside the sample with the insulating film sandwiched between the sample and the sample stage. Moreover, this polarization brings about the static electricity, which causes the sample and the sample stage to adhere to each other. This static-electricity-based adhesion force (i.e., electrostatic adhesion force) allows implementation of an enhancement in the heat conduction efficiency between the sample and the sample stage, thereby allowing implementation of an enhancement in the controllability of the sample temperature.
As an example of conventional technologies like this, there has been known a technology which is disclosed in JP-A-57-64950. In this conventional technology, the film thickness of the insulating film is made thin enough so that the sufficient electrostatic adhesion force becomes obtainable. Concretely, this film thickness is set at about 50 to 200 μm.
Furthermore, as is the case with the electrostatic-adhesion-dedicated electrode, the above-described heater is also deployed on the lower-surface side of the insulating film. As a result of this configuration, the thinner the film thickness of the insulating film is made, the smaller the heat resistance becomes which arises from the heater-deployed lower surface to the sample-mounted surface. This condition allows implementation of an enhancement in the temperature controllability of the sample-mounted surface.